This invention relates to vehicle mounted devices for holding drill rods when they are raised or lowered in a drill hole, and for unthreading and disconnecting drill rod sections. Typically drill rods are furnished in ten foot lengths. There may be several hundred feet of drill rods in a hole. When coming out of the hole, the rods need to be disconnected in ten or twenty foot lengths. In the past, a rod holder has been secured to the back end of a vehicle. The rod holder usually has had a pair of clamp jaws with cam surfaces that are positioned to grip the rod that is being driven by driving mechanism mounted on the vehicle. The jaws are removed during the drilling, and then are installed in a receiver to clamp the drill rod between them. The jaws prevent the rod from moving axially and tend to inhibit it from turning. In practice, when drilling a hole, the drill rods are likely to shift slightly due to movement of the vehicle. Conventional clamps are not equipped to cope with this problem. Also, it is frequently difficult to break-out sections of rods that are threaded together. The drill string is clamped by the jaws immediately below a joint, and the joint is commonly broken manually, with pipe wrenches.
One of the objects of this invention is to provide a rod holding device that is simple and at the same time provides ready adjustment to accommodate misalignment of the vehicle and drill string.
Another object is to provide a rod holding device that hydraulically clamps drill rods with two opposing hydraulic cylinders.
Another object is to provide a rod holding device that is pivotally mounted and will swing on and off the drill hole.
Another object is to provide such a device that can be moved vertically to adjust its height for ease in transporting and convenience of use.
Another object is to provide such a rod holding device with a break-out device that is simple and rugged and that is power actuated to break the joint of a drill string.
Other objects will occur to those skilled in the art in light of the following description and accompanying drawings.